Oh you poor thing, what an absolute nightmare! I wouldn't cope with that even if it was my own Mum doing it.
That is completely disrespectful of her, and if you're not comfortable speaking to her about it (or, as it sounds like, you've tried and she's not listening anyway) your DP needs to be the one to do it. He needs to be able to tell her that neither of you will accept any visitors without prior calls to ask whether it's convenient for them to come for a start! Often men hate having confrontations with their parents, and that is understandable, but what she is doing will eventually put a strain on your relationship. It sounds like she is turning up and staying the night when your DP is home, so he is going to have to be the one to tell her that it's not acceptable, and that, no, she cannot stay over.
My DH works away for 2 weeks at a time and both of our parents would never dream of just rocking up to our house (actually, his Dad did it once, we were 'otherwise occupied', he heard it and I can assure you he's never made that mistake again ). Even my own Mum will always ask if we have any spare time for her to get to see DH when he is home, and completely understands if we say "not this break, we already have 3 other people we're catching up with and we'd like the rest of the time just together".
I feel very sorry for you, that is a very hard position to be in. I really hope you can get it sorted out